Transcript for Celebrity Doppelgangers Inspire 'GMA' to Search for Look-a-Likes

7 billion people in the world, all of us unique. But out there somewhere do we all have a double? Shn who looks just like us? Gotta be, right? And double trouble can show up when you least expect it. Max found his in a 16th century painting at the philadelphia museum of art. We're hoping that maybe we can find out if it is an ancestor. Reporter: Then there's the duchess double. Heidi was working at a rate resz when customers pointed out she looks just like kate middleton. It's fun. Reporter: Her royal look now commands a $1,000 appearance fee. Being a celebrity look-a-like can mean big bucks. I think everybody has a double out there. Whether they're famous or not. Reporter: She's doubled as madonna. Somebody comes to me and sarks I kind of look like -- we can refine it. Reporter: From hollywood power couple brad and angelina. I got my shirt ripped off one time by some girls. It was hilarious. They thought I was him. Reporter: To oprah. I am oprah! Reporter: There's cher. People ask for autograchs or tell me stories about when they SAW CHER IN THE '70s. Reporter: And johnny depp. It's a great gig. Reporter: What about our Are the doubles out there? You sent in th pictures. We september them to our judges. My better half, ali wentworth, model cynthia bailey, and comedian sherrod small. Join us as we come face to face , maybe ourselves. Our fate is in their hands. For sure. Right now. I don't know.

This transcript has been automatically generated and may not be 100% accurate.